1. Field
Exemplary embodiments of the present invention relate to data transmission technology, and more particularly, to a technology for preventing crosstalk occurring during the data transmission.
2. Description of the Related Art
Generally, in a high-speed data transmission, jitter may be caused in the transmission data/signal by Inter-Symbol Interference (ISI), random noises, etc. Specially, crosstalk may cause the jitter of the transmission signal to affect the data transmission.
FIG. 1 illustrates a diagram for showing crosstalk occurring in a plurality of lines LINE_0 to LINE_3 through which data are transmitted.
The data may be loaded on the respective lines LINE_0 to LINE_3 in order from the leftmost data of the drawing to the rightmost data thereof.
Crosstalk may occur due to capacitance appearing between adjacent two data lines. The crosstalk feature may become more serious when, among adjacent three lines, two lines respectively adjacent to a central line are loaded with data which have a level transition opposite to that of data loaded on the central line. In this case, the data pattern is referred to as a 2-aggressor-1-victim pattern.
Numeral references ‘101’, ‘102’, ‘103’, ‘104’, and ‘105’ of FIG. 1 illustrate the pattern. Referring to the pattern ‘101’, the data of a second line LINE_1 transitions from a logic low level ‘L’ to a logic high level ‘H’, but the data of a first line LINE_0 and a third line LINE_2 all transition from a logic high level ‘H’ to a logic low level ‘L’. Therefore, it may be difficult to make the data transition of the second line LINE_1 due to crosstalk. Likewise, since the data transition of the central line is opposite to the data transition of the lines LINE_0 and LINE_2 or LINE_1 and LINE_3 respectively adjacent to the central line LINE_1 or LINE_2 as shown in the patterns ‘102’, ‘103’, and ‘105’, it may be difficult to make the data transition of the central line LINE_1 or LINE_2.
In case of the pattern ‘104’, the data of the second line 1 LINE_1 and the data of the third data line LINE_2 may have difficulty in transitioning, because the data transition of data lines LINE_0 and LINE_2 adjacent to the second line LINE_1 and the data transition of data lines LINE_1 and LINE_3 adjacent to the third line LINE_2 are made in opposite directions to the data transitions of the second and third data lines LINE_1 and LINE_2, respectively.
FIG. 2 illustrates a conventional scheme for preventing a crosstalk in a transmitting chip that transmits data.
Referring to FIG. 2, a transmitting chip 200 includes a data pattern sensing unit 210, a crosstalk prevention unit 220, and a data output circuit 230.
The data pattern sensing unit 210 senses the pattern of the data D0 to D7 to be transmitted by the transmitting chip 200 and decide whether a crosstalk may occur in any data line of first to eighth data lines LINE_0 to LINE_7. For example, the data pattern sensing unit 210 senses if the data of adjacent data lines have the same transition as the patterns ‘101’ and ‘105’ shown in FIG. 1.
The crosstalk prevention unit 220 performs an operation for preventing crosstalk from occurring in the data to be transmitted based on the sensing result of the data pattern sensing unit 210. The occurrence of the crosstalk may be prevented by (1) changing a delay value of a data, (2) changing a driving force of a data, or (3) changing a logic value of a data. In case that (1) the delay value of a data is changed, the influence of crosstalk may be reduced by increasing the delay value of an aggressor data or by decreasing the delay value of a victim data. The influence of crosstalk may be decreased (2) by controlling a victim data with a strong driving force or by controlling an aggressor data with a slightly week driving force. The data pattern, which may cause a crosstalk, may be removed (3) by inverting data contained therein.
The data output circuit 230 outputs data obtained from a crosstalk prevention operation performed by the crosstalk prevention unit 220 to the outside of the transmitting chip 200.
In short, according to the conventional crosstalk prevention scheme, the pattern of transferred data is sensed and a crosstalk prevention operation is performed based on the sensed result.
FIGS. 3A and 3B illustrate the first to eighth data lines LINE_0 to LINE_7 arrayed between the transmitting chip 200 and a receiving chip 300. The capacitors illustrated in FIGS. 3A and 3B indicate parasitic capacitor components existing between the first to eighth data lines LINE_0 to LINE_7.
Referring to FIG. 3A, the array of first to eighth data pins 0 to 7 of the transmitting chip 200 matches the array of the first to eighth data lines LINE_0 to LINE_7 coupled to the respective data pins. That is, the data pin number, for example, ‘0’, is identical to the position order ‘0’ of corresponding data line LINE_0. Therefore, sensing the data pattern shown in FIG. 2 and performing a crosstalk prevention operation based on the sensed result may decrease the influence of crosstalk.
Referring to FIG. 3B, the array of first to eighth data pins 0 to 7 is different from the array of the first to eighth data lines LINE_0 to LINE_7. That is, the data pin number of the transmitting chip 200, for example, ‘0’, is not identical to the position order ‘1’ of corresponding data line LINE_1. The transmitting chip 200 performs a crosstalk prevention operation based on adjacent data pins of the transmitting chip 200. Since the first to eighth data lines LINE_0 to LINE_7 have position orders different from respective data pin numbers of the transmitting chip 200, the crosstalk prevention operation shown of the scheme in FIG. 2 may not performed on the array of data lines shown in FIG. 3B. For example, the transmitting chip 200 senses the data pattern of the third data pin 2 and the fifth data pin 4, which are adjacent data pins of the fourth data pin 3 coupled to the fourth data line LINE_3, and performs the crosstalk prevention operation for the data of the fourth data line LINE_3. However, the fourth data line LINE_3 is actually adjacent to the second data line LINE_1 and the eighth data line LINE_7 and the above crosstalk prevention operation based on the pin array may not work on the line array. That is, since the array of the first to eighth data pins 0 to 7 of the transmitting chip 200 are different from the array of the first to eighth data lines LINE_0 to LINE_7, the crosstalk prevention scheme based on the data pattern of the first to eighth data pins 0 to 7 may not appropriately performed on the array of the first and eighth data lines LINE_0 to LINE_7 shown in FIG. 3B.
As the data transmission rate becomes higher, the bandwidth of data, which is the number of data lines, is increased as well. Accordingly, a semiconductor device fabrication process is being complicated, such as fabrication of a multi-layered circuit board. As a result, as shown in FIG. 3B, the array of the first to eighth data pins 0 to 7 over the transmitting chip 200 may be desirable to be different from the array of the first to eighth data lines LINE_0 to LINE_7 in a position order over a circuit board.
Therefore, it is desired to properly perform a crosstalk prevention operation even though the array of the first to eighth data pins 0 to 7 of the transmitting chip 200 is different from the array of the first to eighth data lines LINE_0 to LINE_7, each coupled to a corresponding data pin.